Testimony of people on the Azores archipelago 700 years earlier than expected

An international team of researchers has found evidence that people were living on islands in the Azores archipelago some 700 years earlier than previous evidence had shown. In their article, published in Proceedings of the National Academy of Sciences, the group describes its study of sediment cores taken from the lakes of some of the islands of the archipelago.

Due to the lack of other evidence, historians believe that people first arrived in the Azores in 1427, when the Portuguese sailor Diogo de Silves landed on the island of Santa Maria. Soon after, others from Portugal arrived and took up residence in the archipelago. In this new effort, researchers found evidence that humans lived on some of the Azores islands around 700 years earlier.

Seeking to learn more about the history of the Azores, researchers began collecting sediment samples from several lakes on the islands and studying them to see what they might reveal. Sediment samples can serve as historical evidence because material in the air that falls on the surface of a lake and then to the bottom of the lake is covered with new layers of sediment over time.

Analysis of sediment cores showed an increase in 5-beta-stigmasterol in a layer of core dated between 700 CE and 850 CE, taken from Lake Peixinho. The compound is typically found in the feces of cattle, such as cows and sheep, none of which lived in the Azores before humans arrived. They also found an increase in charcoal particles (suggesting that large fires had burned) as well as a decrease in pollen from native trees. The results suggest that someone burned the forest to provide more land for livestock. Researchers found similar evidence in carrots taken from Lake Caldeirão, which is on a different island, although it appeared about a century later. And they found evidence of non-native ryegrass in the sediment of a lake on a third island.

The finds present strong evidence that humans inhabited the archipelago for hundreds of years before the Portuguese arrived. Researchers believe they were likely Nordic sailors, noting their accomplishments in sailing along the coasts of many parts of Europe.

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